1. Field of the Invention.
This invention relates to a novel method for polymerizing acetylene utilizing a lithium dicyclopentadienyl titanium hydride catalyst.
2. Brief Description of the Prior Art
Partially crystalline forms of polyacetylene, in the cis or trans configurations, when doped with controlled amounts of an electron-attracting species such as a halogencontaining compound, specifically iodine or arsenic trifluoride, are known to exhibit increases in conductivity over a remarkably wide range of up to about 11 magnitudes. See J. Am. Chem. Soc. Vol. 100, pp. 1015-1017 (1978). The "doped" polymers are capable of functioning as electrical conductors or semi-conductors.
Catalytic methods for synthesizing polyacetylene in its respective cis and trans configurations, are well known in the art and include the use of Ziegler-type catalysts, described for example in J. Poly. Sci. Polymer Chemistry, Ed. Vol. 12, 11-20 (1974); the use of copper-aluminum-spinel solids, as described in Kinet. Katal. 12 (4), p. 974 (1971), Chem. Abstracts, 76, 15005 (1972); and the use of dicyclopentadienyl vanadium as described in Japanese Pat. No. 70 08,980 (1970), Chem. Abstracts, 73 67036s (1970).
The reference, Bull Chem. Soc. Japan, Vol. 38, 859 (1965), describes a method for polymerizing acetylene which involves a "titanocene"-type catalyst. However, subsequent work described in J. Am. Chem. Soc., Vol. 92, pp. 6182-6185 (1970), disclosed that the above "titanocene" material, as prepared by the reduction of dicyclopentadienyltitanium dichloride with sodium amalgam, actually used as a catalyst is in fact a dimer of cyclopentadienyl fulvalene titanium hydride.
The references of Guido Pez in J. Am. Chem. Soc. 98, 8070 (1976), U.S. Pat. No. 3,776,932 (1973), U.S. Pat. No. Re. 29,368 (1977) and U.S. Pat. No. 4,024,169 (1977), Allied Chemical being the assignee, disclose novel cyclopentadienyl titanium compounds useful in removing gaseous nitrogen from admixture with argon.
U.S. Application Ser. No. 957,392, filed Nov. 3, 1978 (assigned to Allied Chemical) by Guido Pez describes novel lithium dicyclopentadienyl titanium hydride compounds which are useful as catalysts in the dimerization of ethylene to 1-butene. However, no mention or suggestion is made in the above-described reference as to the use of lithium dicyclopentadienyl titanium hydride compositions as catalysts in the polymerization of acetylene.
There is a continuing need in the art for new, inexpensive and conveniently prepared compositions which can function as catalysts to efficiently polymerize acetylene into its respective cis and trans forms.